This thesis describes several concepts associated with the transmission of multimedia services over mobile radio access networks. The error performance and traffic requirements of real-time video transmission over the General Packet Radio Services (GPRS) access network and its successor Enhanced-GPRS is examined. In view of this. video error resilience techniques which exploit channel prioritisation mechanisms are introduced with a view to increasing the robustness of received video sequences encoded with MPEG-4 to channel errors. These include stream prioritisation using unequal error protection and region-of-interest prioritisation for use in multiparty communications and streaming applications. A new forward-error correction scheme for EGPRS which uses iterative serially-concatenated convolutional-Reed Solomon codes is designed and is shown to significantly enhance the error performance for real-time services. A study of (he use of backward error correction mechanisms when transmitting streaming multimedia services is carried out, and a new retransmission scheme is introduced to increase the capacity of the radio access network when supporting streaming services

In a packet radio network, multiple terminals broadcast information over a shared communications medium. Messages are transmitted from a source terminal to a destination terminal over multiple relays or hops. The actions of one terminal in the network directly affect the actions of other terminals within its range. The analysis of packet radio networks is complex because system performance depends on the topology of the terminals in the network along with the random access protocol used. Researchers have been unable to model a packet radio network in its most general form. In this project, a model is developed for specific topologies of a packet radio network with a given random access protocol. The sponsor of this project has developed a packet radio network for an indoor wireless alarm system. At the start of the project, the effect of message collisions on system performance was unknown. As a result of this research, a collision model for the network has been developed for topologies of four, five, and six alarm units. The model has been validated with actual system testing. Furthermore, the effects of indoor propagation on system performance have been studied. The results of this work have led to the development of an installation plan for the indoor wireless alarm system. / Master of Science

This research investigates the application of multiuser interference suppression to direct-sequence code-division multiple-access (DS-CDMA) for peer-to-peer packet radio networks. The emphasis of this work is to develop and validate efficient interference suppression techniques through selective cancellation of interference; next, the combination of interference suppression with error correction coding is studied. A decoder-assisted frame synchronization technique is proposed for future packet radio system. The performance of DS-CDMA in packet radio networks suffers from the near-far problem. This near-far problem can be alleviated by using either a multiuser receiver or a single-user adaptive receiver along with centralized or distributed power control. The first part of this dissertation compares the use of these receivers in a peer-to-peer environment. Next, we investigate how interference cancellation can be combined with forward error correction coding for throughput enhancement of the system. Although receivers using interference suppression are simple in structure, the performance degrades due to the lack of exact knowledge of the interfering signal in cancellation and also due to biased decision statistics for the parallel cancellation case. We consider a system that employs both partial parallel interference cancellation and convolutional coding. Information is shared between the operations of interference cancellation and decoding in an iterative manner, using log-likelihood ratios of the estimated coded symbols. We investigate the performance of this system for both synchronous and asynchronous CDMA systems, and for both equal and unequal signal powers. Finally, a new code-assisted frame synchronization scheme, which uses the soft-information of the decoder, is proposed and evaluated. The sync bits are placed in the mid-amble, and encoded as a part of the data sequence using the error correction encoder to resolve time ambiguities. This technique is applied for turbo decoder-assisted frame synchronization. The performance improvement of these proposed techniques over conventional synchronization techniques is explored via simulation. / Ph. D.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper presents the results of a feasibility study undertaken by the University of Salzburg (Austria), investigating the autonomous acquisition of environmental data in a global network. A suggested application which is used as the basis of this paper is a volcano monitoring system which would be able to track the activity of a volcano and act as a disaster warning system. The background Volcano observation data required for such a system is covered, before discussing the concepts for sensor data acquisition, storage and processing. A final analysis is then presented of the opportunities for the transmission by packet radio (both terrestrial and satellite).

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Research on earthquakes and volcanos is of particular importance in seismic instable regions. To improve opportunities of research and civil defence, continuous coverage of seismic activities of a large area at a certain time is necessary. This paper deals with the issues concerning the collecting of environmental data by a number of autonomous field stations and their transmission to central station through a cost effective low bandwidth packer radio data network. This paper deals with the acquisition, preprocessing and transmission of seismic data. Therefore, a prototype system is discussed, which will be developed at the University of Salzburg, Austria.

Internet and mobile phones are two of the most popular innovations of information technology in recent times. As the number of Internet and mobile phone users continues to grow, it is expected that mobile services that enable e-commerce would provide new business opportunities constantly. With the expected rapid growth of mobile commerce, factors affecting the adoption of relative technologies have recently turned into a critical topic of business research. / While the final success of 3G networks is still to be determined, GPRS-enabled mobile phones have been publicly available since 2001. In the area of mobile technologies that enable mobile commerce, GRPS is currently the most popular mobile phone service that allows users to execute business transactions through Internet. The innovation of GPRS technology offers mobile services with the advantages of low cost and fast speed, and thus becomes an ideal tool to be used for mobile commerce. Realizing the advantages of GPRS and the importance of relative studies to the mobile industry, this research aimed to address the issues of user acceptance and behavioural intentions on GPRS-enabled mobile phones. / In Taiwan, the penetration rate of mobile phone had reached 114% and made the number one in the world. This high penetration rate made Taiwan a practical site for studying mobile technology acceptance. This research was therefore proposed to be conducted in Taiwan to better understand the user adoption of mobile phones. This study first reviewed the development of mobile technologies as well as the theoretical background for the research. The model of decomposed theory of planned behaviour was then adopted as the research framework based on previous empirical studies of new mobile services. Fourteen hypotheses were developed to address the key research question as to the factors affecting the adoption of GPRS mobile phones in Taiwan. An online questionnaire was implemented for data collection from Internet users. Data analysis followed for hypotheses testing based on structural equation modelling. The study results show that cost and speed, perceived usefulness, image, risk, compatibility, peer influence, self-efficacy, and facilitating conditions are found to significantly influence the adoption intentions of GPRS technology. / This study on the adoption of GPRS technology is important for enterprises that are planning to offer mobile services. The results of this research may offer directions for industrial practitioners in the field to improve the diffusion and acceptance of GPRS. Such research results can also provide knowledge for business executives to better understand the primary concerns of mobile customers and thus develop mobile services and technologies more strategically. Other managerial implications and suggestions for future research are also discussed at the end of this dissertation. / Thesis (DBA(DoctorateofBusinessAdministration))--University of South Australia, 2005.

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Next generation wireless systems are being designed to provide ubiquitous broadband link access to information infrastructure. Diversity techniques play a vital role in supporting such high speed connections over radio channels by mitigating the detrimental effects of multiuser interference and multipath fading. Equal gain combining (EGC) diversity receiver is of practical interest because of its reduced complexity relative to optimum maximal ratio combining scheme while achieving near-optimal performance. Despite this, the literature on EGC receiver performance is meager owing to difficulty in deriving the probability density function of the diversity combiner output. This problem is further compounded when the diversity paths are correlated. Since spatial, pattern, or polarization diversity implementations at a mobile handset are usually limited to a small diversity order with closely spaced antenna elements (owing to cost and ergonomic constraints), any performance analysis must be revamped to account for the effects of branch correlation between the combined signals. This thesis presents a powerful characteristic function method for evaluating the performance of a two-branch EGC receiver in Nakagami-m channels with non-independent and non-identical fading statistics. The proposed framework facilitates efficient error probability analysis for a broad range of modulation/detection schemes in a unified manner. The thesis also examines the efficacy of an average diversity combiner in slotted direct sequence spread-spectrum access packet radio networks. A two-dimensional EGC diversity combining scheme is introduced, wherein a corrupted packet is retained and combined with its retransmission at the bit level to produce a more reliable packet. The mathematical analysis of the average diversity combiner presented in this thesis is sufficiently general to handle generalized fading channel models with independent fading statistics for a myriad of digital modulation schemes. / Master of Science

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The intelligent vehicle navigation system is a multifunctional and complex integrated system that uses autonomous vehicle navigation, geography information, database system, computer technology, multimedia technology and wireless communication. In this paper, an autonomous navigation system based on embedded hardware and embedded operation system that is Linux is proposed. The system has advantages of low cost, small mass, multifunction and high stability, especially connecting with Internet.